海南椰子水氢氧稳定同位素特征与环境影响因素分析OA

To mitigate the lack of background data supporting the authenticity regulation of Hainan coconut water,this study collected a total of 72 samples,comprising natural coconut water and local tap water(as a potential exogenous addition medium)from Wenchang,Qionghai,and Ding'an in Hainan Province,and determined their δ2H and δ18O values.The methods including the Mann-Whitney U test,one-way analysis of variance(ANOVA),Pearson correlation analysis,and linear discriminant analysis(LDA)were used to analyse the geographical distribution patterns,environmental influencing factors,and variation characteristics of hydrogen and oxygen stable isotopes in coconut water relative to local tap water.The results showed that the overall δ²H and δ18O values of coconut water were-5.02‰±4.83‰and-0.21‰±1.24‰,respectively.Significant differences were found in the δ²H values among the three origins(P<0.05),and the δ18O value of the Wenchang origin was significantly higher than those of Qionghai and Ding'an(P<0.05).The LDA model constructed based on these values achieved an original classification accuracy of 88.9%and a cross-validation accuracy of 83.3%.Additionally,the δ2H and δ18O values of coconut water exhibited differentiated correlations with various environmental factors.Specifically,δ2H showed negative correlations with annual precipitation and annual sunshine duration(r=-1.00 and-0.94,respectively),and a positive correlation with latitude(r=0.82).In contrast,δ18O exhibited positive correlations with mean annual temperature and longitude(r=0.93 and 0.99,respectively),while showing negative correlations with distance from the sea and annual sunshine duration(r=-0.99 and-0.93,respectively).The δ²H and δ18O values of coconut water were significantly higher than those of tap water.Furthermore,a significant positive correlation was observed between the isotope values of coconut water and tap water(δ2H:r=0.70;δ18O:r=0.61;P<0.01).This study elucidated the differentiation characteristics of δ2H and δ18O values in Hainan coconut water relative to local tap water and their correlation patterns with environmental factors,and established a geographical discrimination model for the three origins of Wenchang,Qionghai,and Ding'an.These findings provide background data support for the future construction of adulteration detection models for coconut water.